Not for my son, or a future daughter.
The 'so they know its a girl' argument is so ridiculous, I can hardly respond. 'So what?' Is what I say.
Because of the clothes that are available - my son wears mostly dark colors, blues, reds and greens. Mostly blues actually, everytime he leaves the house - he gets mistaken for a girl. He has luscious shiny curly hair - but I'm not going to cut it, just so he can abide by what 'boys look like.'
Nor am I going to dress him in Monster Truck shirts to Prove that he has a certain genitals.
I see earrings to be the same thing.
"Look, she's a GIRL." Blah.
Way to encourage your kids to abide by cultural stigma.
If my son wants to wear a dress, I'll help him pick out the fabric, and we'll make it together (when he realizes it is harder to play in, he may think otherwise.)
If my daughter wants to pierce her ears, I'll find the reasoning, and discuss it with her. Until she's old enough to have that conversation, no way.
Theres a difference between putting your baby girl in a dress and altering her body to conform to whats 'cute'.